U.S. Pat. No. 6,930,818 describes how microstructures, such as microcups, may be prepared using an embossing process. The embossing process may be carried out roll to roll using an embossing assembly comprising a rotating drum. There are many advantages of using such a roll to roll process, such as low cost and high yield.
U.S. Pat. No. 6,930,818 also describes how the microcups may be filled with a display fluid which becomes an essential part of a display device.